To use REFPROP 9.1 in MATLAB, you need a wrapper file (often provided in the MATLAB subfolder of the installation). In MATLAB, use addpath('C:\Program Files (x86)\REFPROP') . Use the refpropm.m function to call properties.
At the bottom, select from the "Manage" dropdown and click Go . refprop 91 install
Installing REFPROP 9.1 is straightforward, but the real work lies in the for your specific external software. Always ensure your .dll files are in a location where your system's PATH environment variable can find them. To use REFPROP 9